1. Field of the Invention
The invention relates to lawnmowers and to cutter decks usable there with. More particularly, the invention relates to a side-to-side leveler for a lawnmower cutter deck.
2. Discussion of the Related Art
Riding lawnmowers and some larger walk behind lawnmowers have multi-bladed cutter decks supporting two, three, or even more cutting blades. Such lawnmowers may cut a strip of grass from 24 inches to 72 inches wide or even more. The cutter deck typically can be raised from a cutting height located near the ground to a travel height located above the ground. The cutting height also can be adjusted by raising or lowering the cutter deck through a more limited stroke and latching the cutter deck in position.
The cutter deck of any lawnmower must be positioned generally parallel to the ground to maintain an even cut. Factors such as initial manufacturing tolerances and subsequent wear in the lawnmower frame, the cutter deck, and the cutter deck supports hinder cutter deck leveling both at initial manufacture and over time. Many cutter decks therefore incorporate some mechanism to perform limited “leveling” of the cutter deck. For instance, some lawnmowers permit “pitch” or “for and aft” leveling by adjusting the length of adjustable links coupling front and rear cranks to one another. The cranks are rotated in unison during normal operation to move the deck between its cutting and transport positions and to vary the cutting height. By rotating the front and rear cranks relative to one another, the heights of the upper end of the deck supports at the front and rear of the deck are altered relative to one another, altering deck pitch.
Cutter decks often are suspended from the lawnmower frame by chains so that the deck may rise up and over obstruction upon contact without interference from the structure coupling the cutter deck to the lawnmower frame. In this case, pitch adjustment adjusts the height of the upper ends of the front chains relative to the rear chains.
Many existing cutter decks lack any mechanism for “side-to-side leveling” i.e., for adjusting the height of one side of the cutter deck relative to the other independently of any pitch adjustment. Those cutter decks that do incorporate measures for “side-to-side leveling” suffer from distinct drawbacks and disadvantages. For instance in one known system, the bottom of the front chain on one side of a suspended cutter deck is attached to a bracket on top of the cutter deck via a bolt extending through a vertical slot in the bracket. The cutter deck can be leveled by loosening the bolt and moving it along the slot in the bracket. However, the cutter deck cannot be leveled with the chain under tension because the weight of the cutter deck will simply pull the cutter deck to its lowermost position in which the bolt bottoms out against the top of the slot. As such, side-to-side leveling requires the operator to measure the deck height at both sides of the cutter deck, estimate the amount of adjustment required, and then lift the cutter deck and brace it to remove the tension from the chain. The operator then must loosen the bolt and move it to the position in the slot estimated to provide the desired adjustment, tighten the bolt, and remove the brace from the cutter deck so that it is again supported by the chain. The operator then repeats the measurements at both sides of the cutter deck and repeats the adjustment procedure as required on a trial and error basis until the deck is leveled. The resulting leveling process can be very tedious because of the trial and error basis for it. It is also relatively labor intensive because the operator must repeatedly lift the cutter deck to remove the tension from the chain prior to loosening the bolt and then retighten the bolt and lift the cutter deck again to remove the brace after the bolt is repositioned along the slot.
Other proposals have been made to permit side-to-side leveling of cutter decks without lifting the cutter deck. See, e.g., U.S. Pat. No. 4,869,057 to Siegrist and U.S. Pat. No. 5,956,932 to Schmidt. However, all of these systems are relatively complex, and all rely on fixed linkages that are not compatible for use with a suspended cutter deck.
The need therefore exists to provide a side-to-side leveler for a suspended cutter deck that permits the deck to be leveled while the chains supporting the deck are under tension.
The need also exists to provide a side-to-side deck leveler that is easy to use and that provides for precise adjustment over a relatively wide range.